The diminutive nature of a modern digital camera allows itself to become a convenient and popular additional feature of portable consumer electronic devices such as smart phones, tablet computers, laptop computers, and so forth. An image sensor including an array of image sensing pixels is used primarily in the digital camera that receives and converts incident light into electrical signals. Some electronic devices may include both image sensing elements as well as phase detection (PD) sensing element within a single image sensor, and such arrangement allows for a pixel-level auto-focusing precision. However, due to manufacturing design constraints and defects, when the incident light is not effectively confined to the generated sensing element, optical crosstalk becomes problematic such that its adjacent sensing elements would then be adversely affected, and thereby causes a degradation of image quality.